Quote:Critics, of course, will raise all kinds of objections to this bizarre scenario. Many we have raised ourselves – like the low probability of Galileo’s plutonium even surviving entry – at 108,000 miles per hour! – to reach the necessary “crush depth” for implosion.

A far more serious objection is that the nuclear fuel Galileo carried – plutonium-238 – while ideal as a sustained heat source for making electricity via thermoelectric technology, is NOT traditionally viewed as a fissionable material appropriate for creating nuclear explosions. The plutonium isotope vastly preferred for the original “Fat Man” weapon was plutonium-239 – which, by not emitting an excess of neutrons prior to achieving supercriticality, allowed the construction of an actual implosion plutonium weapon.

You nailed it again CC. lol Here's more for you - Galileo's entry into Jupiter's atmosphere and the eyes of Jupiter.

The obejctions raised by Hoagland here, he also finds the way to get around them, btw.

He states, and this has been shown now by many sources, that Pu-238 is indeed capable of a fissile nuclear fission reaction. The yield just won't be as nice as Pu-239.

As far as survivability of what went into Jupiter with the Galileo spacecraft and probe, there are two different elements. One is the LWHRU's, 17 of which went into Jupiter protected by a actual heatshield. We know these Pu-238 fuel capsules survived because they went in with the probe that survived entry.

Secondly, we have 144 GPHS-RTG fuel pellets that went into Jupiter on 9-21-03 with the Galileo spacecraft. Although the speed of entry was very high, these pellets were very well-protected with several layers of heatshields and a final clad.

With any entry/re-entry into a planet the most robust elements survive. On Earth, for instance, up to 40% of a craft can survive atmospheric entry. The average is 25% of the craft (the most robust elements).

What are the most robust elements on Galileo? The fuel pellets we spoke of.

Pyrolitic graphite aeroshells of several layers, then an iridium-based clad protecting the plutonium fuel. These were designed to survive such a hot entry/re-entry because of safety concerns on Earth. Even considering a hotter entry for Jupiter compared to Earth, a few percent of the 144 GPHS-RTG fuel pellets did survive Jovian entry. So we have to take the next step and find out what these fuel pellets are capable of, the ones that survived entry into Jupiter.

The next step is to find out the potential for further survivabily of both the LWHRU and the GPHS-RTG fuel pellets as they descend further into the depth of Jupiter.

Quote:The amount of mass you need packed together to get a runaway chain reaction is called the critical mass. For plutonium 238, the kind that was on Galileo, you need about 10 or so kilograms (22 pounds) all packed tightly into a ball. Galileo had more than that amount on board, but (and this is a huge but) it was spread out in smaller pieces. The RTGs extend along a long boom, a rod that extends out from the main body of the spacecraft, and not in a way that works as a fission bomb. There are 72 separate chambers where the Pu238 was stored, and each piece had a sub-critical mass. You would have to compress those pieces together to make them critical and cause a fission reaction.

But that could not happen. Why not? Because Galileo entered Jupiter at a speed of about 100,000 miles per hour. At that speed, the pressure would tear the spacecraft apart. It slows as it passes through denser atmosphere, of course, but the pressures would be so high at those velocities that Galileo would be shredded. As the pieces fall off, they are heated due to compressing the air in front of them. This is why meteors get hot, in fact, and at these speeds the metal on Galileo would melt in short order. This would release the plutonium, dispersing it.

So instead of compressing it, as the pseudoscientists claim, the plutonium would actually get strewn through Jupiter, making it literally impossible to explode. So step one -- Galileo becoming a fission bomb -- cannot happen.

(07-12-2016, 04:47 PM)UniqueStranger Wrote: The following seems more plausible to me.

Quote:The amount of mass you need packed together to get a runaway chain reaction is called the critical mass. For plutonium 238, the kind that was on Galileo, you need about 10 or so kilograms (22 pounds) all packed tightly into a ball. Galileo had more than that amount on board, but (and this is a huge but) it was spread out in smaller pieces. The RTGs extend along a long boom, a rod that extends out from the main body of the spacecraft, and not in a way that works as a fission bomb. There are 72 separate chambers where the Pu238 was stored, and each piece had a sub-critical mass. You would have to compress those pieces together to make them critical and cause a fission reaction.

But that could not happen. Why not? Because Galileo entered Jupiter at a speed of about 100,000 miles per hour. At that speed, the pressure would tear the spacecraft apart. It slows as it passes through denser atmosphere, of course, but the pressures would be so high at those velocities that Galileo would be shredded. As the pieces fall off, they are heated due to compressing the air in front of them. This is why meteors get hot, in fact, and at these speeds the metal on Galileo would melt in short order. This would release the plutonium, dispersing it.

So instead of compressing it, as the pseudoscientists claim, the plutonium would actually get strewn through Jupiter, making it literally impossible to explode. So step one -- Galileo becoming a fission bomb -- cannot happen.

As already stated, yes, most of the craft did burn up. BUT not the extremely protected fuel pellets, many of these survived. This can be shown and is shown in the book, btw.

As far as "critical mass". This is also covered in the book. Critical mass is greatly reduced when density is increased. Having shown that some fuel pellets survive, what you have as they fall deeper into Jupiter is a "fractional crit" situation. This is where the stated critical mass as 1 bar, is greatly reduced when considering the density increase and pressure as millions of bars.

The book shows a diagram of the compressibility of plutonium as great pressures, the pressures that would be encountered deep inside Jupiter.

The critical mass decreases by a inverse squared relationship of the decrease in volume (therefore density increase). For instance if the total volume of a sphere were reduced by x3 (100% to 33% of original volume), its critical mass potential (Mc) would increase by x9.

In addition to this increase you also have to considered that tampers and reflectors are also getting more efficient with added density and pressure. This would add even more criticality potential. Iridium acts as the primary reflector and the highly compressed hydrogen/helium medium at say 30-40 million bars acts as a secondary tamper/reflector.

The GPHS-RTG fuel pellets start out at roughly oval cylinders and would keep getting compressed to oblate spheres insider Jupiter as the iridium EOS (equation of state) shows no melting occurs for this type of metal cladding even at extreme depths.

With the fraction crit scenario described above, we are talking about a SINGLE PELLET being able to go super. 151 grams is the amount in one GPHS-RTG fuel pellet. It needs a factor of around x75 to get to Mc of supercritical.

This can be accomplised by using increased density combined with increased reflector efficiency. The method has been around since the late 40's. Less material is needed if you can "fractional crit" it.

(07-12-2016, 04:47 PM)UniqueStranger Wrote: The following seems more plausible to me.

Quote:The amount of mass you need packed together to get a runaway chain reaction is called the critical mass. For plutonium 238, the kind that was on Galileo, you need about 10 or so kilograms (22 pounds) all packed tightly into a ball. Galileo had more than that amount on board, but (and this is a huge but) it was spread out in smaller pieces. The RTGs extend along a long boom, a rod that extends out from the main body of the spacecraft, and not in a way that works as a fission bomb. There are 72 separate chambers where the Pu238 was stored, and each piece had a sub-critical mass. You would have to compress those pieces together to make them critical and cause a fission reaction.

But that could not happen. Why not? Because Galileo entered Jupiter at a speed of about 100,000 miles per hour. At that speed, the pressure would tear the spacecraft apart. It slows as it passes through denser atmosphere, of course, but the pressures would be so high at those velocities that Galileo would be shredded. As the pieces fall off, they are heated due to compressing the air in front of them. This is why meteors get hot, in fact, and at these speeds the metal on Galileo would melt in short order. This would release the plutonium, dispersing it.

So instead of compressing it, as the pseudoscientists claim, the plutonium would actually get strewn through Jupiter, making it literally impossible to explode. So step one -- Galileo becoming a fission bomb -- cannot happen.

As already stated, yes, most of the craft did burn up. BUT not the extremely protected fuel pellets, many of these survived. This can be shown and is shown in the book, btw.

As far as "critical mass". This is also covered in the book. Critical mass is greatly reduced when density is increased. Having shown that some fuel pellets survive, what you have as they fall deeper into Jupiter is a "fractional crit" situation. This is where the stated critical mass as 1 bar, is greatly reduced when considering the density increase and pressure as millions of bars.

The book shows a diagram of the compressibility of plutonium as great pressures, the pressures that would be encountered deep inside Jupiter.

The critical mass decreases by a inverse squared relationship of the decrease in volume (therefore density increase). For instance if the total volume of a sphere were reduced by x3 (100% to 33% of original volume), its critical mass potential (Mc) would increase by x9.

In addition to this increase you also have to considered that tampers and reflectors are also getting more efficient with added density and pressure. This would add even more criticality potential. Iridium acts as the primary reflector and the highly compressed hydrogen/helium medium at say 30-40 million bars acts as a secondary tamper/reflector.

The GPHS-RTG fuel pellets start out at roughly oval cylinders and would keep getting compressed to oblate spheres insider Jupiter as the iridium EOS (equation of state) shows no melting occurs for this type of metal cladding even at extreme depths.

(07-12-2016, 04:47 PM)UniqueStranger Wrote: The following seems more plausible to me.

Quote:The amount of mass you need packed together to get a runaway chain reaction is called the critical mass. For plutonium 238, the kind that was on Galileo, you need about 10 or so kilograms (22 pounds) all packed tightly into a ball. Galileo had more than that amount on board, but (and this is a huge but) it was spread out in smaller pieces. The RTGs extend along a long boom, a rod that extends out from the main body of the spacecraft, and not in a way that works as a fission bomb. There are 72 separate chambers where the Pu238 was stored, and each piece had a sub-critical mass. You would have to compress those pieces together to make them critical and cause a fission reaction.

But that could not happen. Why not? Because Galileo entered Jupiter at a speed of about 100,000 miles per hour. At that speed, the pressure would tear the spacecraft apart. It slows as it passes through denser atmosphere, of course, but the pressures would be so high at those velocities that Galileo would be shredded. As the pieces fall off, they are heated due to compressing the air in front of them. This is why meteors get hot, in fact, and at these speeds the metal on Galileo would melt in short order. This would release the plutonium, dispersing it.

So instead of compressing it, as the pseudoscientists claim, the plutonium would actually get strewn through Jupiter, making it literally impossible to explode. So step one -- Galileo becoming a fission bomb -- cannot happen.

As already stated, yes, most of the craft did burn up. BUT not the extremely protected fuel pellets, many of these survived. This can be shown and is shown in the book, btw.

As far as "critical mass". This is also covered in the book. Critical mass is greatly reduced when density is increased. Having shown that some fuel pellets survive, what you have as they fall deeper into Jupiter is a "fractional crit" situation. This is where the stated critical mass as 1 bar, is greatly reduced when considering the density increase and pressure as millions of bars.

The book shows a diagram of the compressibility of plutonium as great pressures, the pressures that would be encountered deep inside Jupiter.

The critical mass decreases by a inverse squared relationship of the decrease in volume (therefore density increase). For instance if the total volume of a sphere were reduced by x3 (100% to 33% of original volume), its critical mass potential (Mc) would increase by x9.

In addition to this increase you also have to considered that tampers and reflectors are also getting more efficient with added density and pressure. This would add even more criticality potential. Iridium acts as the primary reflector and the highly compressed hydrogen/helium medium at say 30-40 million bars acts as a secondary tamper/reflector.

The GPHS-RTG fuel pellets start out at roughly oval cylinders and would keep getting compressed to oblate spheres insider Jupiter as the iridium EOS (equation of state) shows no melting occurs for this type of metal cladding even at extreme depths.

[76] http://www.fas.org/rlg/980826-pu.htm, Reactor-Grade Plutonium Can be used to Make Powerful and Reliable Nuclear Weapons: Separated plutonium in the fuel cycle must be protected as if it were nuclear weapons. Richard L. Garwin Senior Fellow for Science and Technology Council on Foreign Relations, New York Draft of August 26, 1998, accessed 11/21/2010

Most of those sources you posted are theory (could...) and mainly relate to weapons grade plutonium which is 239, not 238.

Wherever I look they are claiming plutonium 238is nonfissible.

From Britannica:

atomic weapons
Atomic bomb: The properties and effects of atomic bombs
When a neutron strikes the nucleus of an atom of the isotopes uranium-235 or plutonium-239, it causes that nucleus to split into two fragments, each of which is a nucleus with about half the protons and neutrons of the original nucleus. In the process of splitting, a great amount of thermal energy, as well as gamma rays and two or more neutrons, is released. Under certain conditions, the...
Nuclear weapon: The fission process
Fission weapons are normally made with materials having high concentrations of the fissile isotopes uranium-235, plutonium-239, or some combination of these; however, some explosive devices using high concentrations of uranium-233 also have been constructed and tested.
Manhattan Project
Only one method was available for the production of the fissionable material plutonium-239. It was developed at the metallurgical laboratory of the University of Chicago under the direction of Arthur Holly Compton and involved the transmutation in a reactor pile of uranium-238. In December 1942 Fermi finally succeeded in producing and controlling a fission chain reaction in this reactor pile at...
Nuclear weapon: Selecting a weapon design
The emphasis during the summer and fall of 1943 was on the gun method of assembly, in which the projectile, a subcritical piece of uranium-235 (or plutonium-239), would be placed in a gun barrel and fired into the target, another subcritical piece. After the mass was joined (and now supercritical), a neutron source would be used to start the chain reaction. A problem developed with applying the...
fissile material
Fissile material
in nuclear physics, any species of atomic nucleus that can undergo the fission reaction. The principal fissile materials are uranium-235 (0.7 percent of naturally occurring uranium), plutonium-239, and uranium-233, the last two being artificially produced from the fertile materials uranium-238 and thorium-232, respectively. A fertile material, not itself capable of undergoing fission with...
Uranium processing
...occurring isotopes, only uranium-235 is directly fissionable by neutron irradiation. However, uranium-238, upon absorbing a neutron, forms uranium-239, and this latter isotope eventually decays into plutonium-239—a fissile material of great importance in nuclear power and nuclear weapons. Another fissile isotope, uranium-233, can be formed by neutron irradiation of thorium-232.
production
Transuranium element: Synthesis of transuranium elements
Plutonium, as the isotope plutonium-239, is produced in ton quantities in nuclear reactors by the sequence
Nuclear reactor: Fissile and fertile materials
Neutron capture may also be used to create quantities of plutonium-239 from uranium-238, the principal constituent of naturally occurring uranium. Absorption of a neutron in the uranium-238 nucleus yields uranium-239, which decays after 23.47 minutes through electron emission into neptunium-239 and ultimately, after 2.356 days, into plutonium-239.

Again, not finding 238 as fissible, but rather fissionable, that is, if Jupiter can provide enough high energy neurons, which we don't know, right?

Quote:the even isotopes, plutonium-238, -240, and -242 are not fissile but yet are fissionable–that is, they can only be split by high energy neutrons. Generally, fissionable but non-fissile isotopes cannot sustain chain reactions; plutonium-240 is an exception to that rule.

The minimum amount of material necessary to sustain a chain reaction is called the critical mass. A supercritical mass is bigger than a critical mass, and is capable of achieving a growing chain reaction where the amount of energy released increases with time.

The amount of material necessary to achieve a critical mass depends on the geometry and the density of the material, among other factors. The critical mass of a bare sphere of plutonium-239 metal is about 10 kilograms. It can be considerably lowered in various ways.

The amount of plutonium used in fission weapons is in the 3 to 5 kilograms range. According to a recent Natural Resources Defense Council report(1), nuclear weapons with a destructive power of 1 kiloton can be built with as little as 1 kilogram of weapon grade plutonium(2). The smallest theoretical critical mass of plutonium-239 is only a few hundred grams.

In contrast to nuclear weapons, nuclear reactors are designed to release energy in a sustained fashion over a long period of time. This means that the chain reaction must be controlled–that is, the number of neutrons produced needs to equal the number of neutrons absorbed. This balance is achieved by ensuring that each fission produces exactly one other fission.